1. Field of the Invention
The present invention generally relates to snap action electrical switches, and more particularly relates to snap action switches that are specifically configured for generally quiet operation.
2. Background Information
The computer mouse was invented in 1968 by Douglas Engelbart (U.S. Pat. No. 3,541,541). Since that time, computer mice have adapted to new technology, whether it be optical movement sensors, scroll-button wheels or ergonomics. One computer mouse component that has not kept pace with the times has been the microswitch. A microswitch used to signify manual input by the mouse's user, particularly through depression of a mouse “button” which thereby depresses a plunger or push button that operates to open and/or close an electrical connection within the microswitch itself.
These types of switches provide the user with tactile (feel) feedback (as the mouse button is depressed force must be overcome, the resulting pressure and the release of the pressure as the switch “snaps” can be felt by the user) as well as the classic “click” sound comprising audible feedback. The “click” sound caused by the internal spring of the switch snapping a movable contact into engagement with a fixed contact. The user can therefore both feel and hear the activation of the switch. In this manner, the two types of user feedback (tactile and sound) provided by use of these switches have remained unchanged and are still signature components of the computer mouse.
The problem addressed by the present invention relates to the audible feedback or “click” sound made upon activation of the mouse button. As computer usage becomes more of an integral part of our society, it becomes more and more desirable to eliminate unnecessary and otherwise bothersome sounds in many common settings where a quiet environment is of value. These settings include, but are not limited to, libraries, computer labs, offices, classrooms, testing centers, apartments, dorm rooms, etc. where unwanted noise would be a distraction. What is needed is a way to decrease or eliminate the “click” sound produced by computer mice while keeping, at least, the tactile feel of a standard computer mouse/microswitch. Embodiments of the present invention solve this need.
A snap action switch (as shown in FIG. 1) typically functions based upon the following principles. A push button contacting a moveable contact member (or “movable member”) is pressed which results in the corresponding movement of the movable member. The moveable member is connected to a spring member positioned and designed to build up and then release applied force beyond a given amount. This produces the “snap” involved in a snap action switch. The spring is configured to be compressed to a certain point based upon its orientation in the switch, and then the compression is released as the spring is moved through an arc of motion. Thus, the user will feel initial resistance and then a release. Also, the spring puts a constant upward pressure on the moveable member, which will allow it to return to its original (default) position following activation.
A typical moveable member has two stable conformations, open and closed. The movable member has a first movable contact and a second movable contact. The first movable contact is configured for contacting an open type fixed contact (second fixed contact) and the second movable contact is configured for contacting a closed type fixed contact (first fixed contact). The movable member's open conformation is the inactivated state and in such a state the movable member's first movable contact will rest in contact with the open type (second) fixed contact. When the push button is pushed, the moveable member will snap into its closed position and its second movable contact will rest in contact with the closed type (first) fixed contact as long as pressure is maintained on the push button. Upon release of said pressure, the moveable member will move back to the open position bringing the first movable contact back into contact with the second fixed contact.
The “click” sound produced by such a microswitch is a result of the moveable contacts being snapped or banged against the fixed contacts. The release of force in the spring member of the switch contributes to the speed at which the movable contacts will make contact with the fixed contacts and thus, to the loudness of the click. Part of the tactile feedback a user feels may also be a function of resonation starting at the fixed contact and moving through the movable contact through the pushbutton and felt by the user. A higher level of tactile feedback is produced, however, by the snap action movement itself.
What is needed is the provision of a snap action switch that retains the tactile feedback of the prior art snap action switches, but which eliminates and/or reduces the audible feedback (clicking) sound typically associated with snap action switches. Embodiments of the present invention solve this need.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.